Detail of the S curve of the Bay Bridge where the truck went over. Notice the mattress still on the span and skid marks. A truck carrying pears plunged off the "S" curve area of the Bay Bridge early Monday morning landing on Yerba Buena island and killing the driver November 9, 2009.

Photo: Brant Ward, The Chronicle

Detail of the S curve of the Bay Bridge where the truck went over....

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A mattress sits above the spot where the truck left the bridge. A CHP spokesman speculated that the bed was in the cab and came out on impact. A truck carrying pears plunged off the "s"-curve area of the Bay Bridge early Monday morning, landing on Yerba Buena Island and killing the driver November 9, 2009.

Photo: Brant Ward, The Chronicle

A mattress sits above the spot where the truck left the bridge. A...

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The cab of the truck lay crushed beneath the new S curve area of the Bay Bridge early Monday morning landing on Yerba Buena island and killing the driver November 9, 2009.

Photo: Brant Ward, The Chronicle

The cab of the truck lay crushed beneath the new S curve area of...

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Detail of the S curve of the Bay Bridge where the truck went over. Notice the mattress still on the span and skid marks. A truck carrying pears plunged off the "S" curve area of the Bay Bridge early Monday morning landing on Yerba Buena island and killing the driver November 9, 2009.

Photo: Brant Ward, The Chronicle

Detail of the S curve of the Bay Bridge where the truck went over....

Image 5 of 6

A truck carrying pears plunged off the "S" curve area of the Bay Bridge early Monday morning landing on Yerba Buena island and killing the driver November 9, 2009.

Photo: Brant Ward, The Chronicle

A truck carrying pears plunged off the "S" curve area of the Bay...

Image 6 of 6

The notorious "S" curve has been the site of over 40 accidents since it was created. A truck carrying pears plunged off the "S" curve area of the Bay Bridge early Monday morning landing on Yerba Buena island and killing the driver November 9, 2009.

Caltrans must move decisively to improve traffic safety on the Bay Bridge, where half measures weren't enough to prevent a deadly accident on tricky stretch of roadway. The skid marks at the start of the new westbound S-curve tell the story: This danger zone is catching drivers off guard.

Drivers need to slow down on a slalom course of temporary pavement, where a truck driver died when his rig shot over the side and plummeted 200 feet to Treasure Island in the predawn hours Monday. Since Sept. 8 when the S-curve section was put in use, 40-plus accidents have occurred on the football-field length of pavement.

Caltrans has posted illuminated warning signs and a reduced speed limit from 50 to 35 mph in the area. But before Monday's fatal incident, the string of accidents should have motivated Caltrans to try extra safety steps. Drivers, who ignored the go-slow advisories, require more obvious warnings. The signs are too late and too subtle.

Bridge planners must re-think how to handle the bridge's heavy load of 260,000 drivers per day. It's a challenge made more difficult by the need to finish construction of an adjacent replacement span and merge it at the juncture where the dangerous S-curve is in use. Drivers will have to navigate this precarious stretch until the new span is connected in 2013.

Caltrans announced some minor adjustments Monday, including its plan to add reflective tape to the barriers along the S-curve and additional advisories on the westbound direction. The curve is not as much of a problem in the eastbound direction coming out of Yerba Buena Island, where most drivers tend to slow down for the tunnel. Those fixes may not be enough.

Our immediate concern is for the daily hazard created by the S-turn. Drivers need to be better warned, and speeders need to be cited. As we saw Monday, it can mean the difference between life and death.